While walking down the street, tim sees a man slumped over grabbing his chest. tim looks around at the other pedestrians who don’t seem concerned. he assumes that, if they aren’t worried, then everything is ok and keeps walking. this is an example of:
diffusion of responsibility.
collective narcissism.
pluralistic ignorance.
the social-responsibility norm.

Pluralistic Ignorance

Explanation:

Pluralistic ignorance can be defined as a situation where a norm or a rule is rejected by a majority of the members of a group but still they follow that on the basis of their erranous assumption that it is acceptable by most of the other people.

Thus the case with Tim where he ignored and assumes that no one is concerned is the case of the Pluralistic Ignorance.